商标侵权收到律师函，怎么处理

7月，收到亚马逊邮件说侵权和直接下架一个变体，随后我将整个listing（包括其他变体）删掉。8月初，收到一封律师函，说我们侵权被告，怎么处理好？
 
Dear Sirs:  
 The Defendants operating the Defendant Internet Stores listed in Schedule A to the Complaint are hereby advised: 
Plaintiffs have charged Defendants with violations of United States federal and state laws prohibiting trademark/copyright infringement and counterfeiting.  A copy of the Complaint; Temporary Restraining Order; Summons; and Preliminary Injunction Motion, Memorandum in Support and Notice of Motion, is attached. 
 
Any answer or other response to the Complaint should be filed with the Clerk of the Court, United States District Court for the Northern District of Illinois, Eastern Division, Chicago, Illinois within twenty-one (21) days after service of this summons upon you. If no appearance or pleading is filed, the Court may render a judgment against the Defendants. 
  
If you do not wish to litigate this matter in court, we can still offer you a settlement for you to get your account back and the case dismissed against you.